Wear-resistant ferrous alloys



United rates Patent WEAR-RESISTANT FERROUS ALLOYS George A. Roberts, Latrobe, Pa., assignor to Vanadium- Alloys Steel Company, Latrobe, Pa., a corporation of Pennsylvania No Drawing. Application March 11, 1955, Serial No. 493,813

Claims. (Cl. 75126) This invention relates to ferrous alloys and in particular to ferrous alloys having high wear resistance. The invention'is based on the discovery that the incorporation of titanium in an alloy steel provides a wear-resistant alloy, and this alloy is especially advantageous.

Heretofore, it was known that wear or abrasion-resistant alloys resulted from the incorporation of vanadium into alloy steels. Thus, wear-resistant higher carbon alloys, having in excess of about 1.25% carbon, resulted from the incorporation of vanadium in a weight ratio to carbon of about 2-411, as disclosed in U. S. Patent No.

2,174,281. Similar results are disclosed in U. S. Patent No. 2,575,219.

Vanadium was incorporated with special advantage in tool steels, especially high speed steels, including both of the tungsten and molybdenum types. The high speed steels include both higher carbon alloys and lower carbon alloys, the latter having about 0.6-1.25 carbon. In the lower carbon alloys, lower vanadium to carbon proportions are permissible, as low as 1:1, and proportions up to 4:1 may also be employed. 7

It has now been discovered in accordance with the invention that improved wear-resistance is imparted to alloy steels, especially high speed steels, by the incorporation or provision of titanium in the alloys. Titanium alone may be added to supply wear-resistance, or titanium and vanadium may be employed together.

Titanium furnishes improved results as compared to vanadium alone, and titanium is in many cases much more effective on a weight basis, 1% of titanium being equivalent to about 1-3%, for the most part, about 2.2%, of vanadium. Titanium increases the wear resistance to a greater extent than vanadium for equivalent proportions. Titanium refines the grain size of the steels to a greater extent than vanadium, thereby improving toughness. It also provides a marked improvement in the cutting performance of high speed steels.

Titanium alone is provided in an alloy in a proportion of about 0.36% by weight. Vanadium may also be provided, optionally, in a proportion up to about 6%, the

. proportion of titanium decreasing with increasing proportion of vanadium, and Vice versa.

With the accompanying use of vanadium, a minimum of about 0.5%, the titanium content may be as low as 0.2% while providing improved results. The titanium range is thus about 0.2-6% by weight. It is generally preferred to employ at least 0.4% of titanium, and it is further preferred to provide at least 0.5% Also, the total maximum amount of titanium and vanadium is about 6%.

In the higher carbon high speed steels, containing carbon in excess of about 1.25%, with a maximum of about 1.5%, the titanium to carbon weight ratio is about 0.7- 4:1. In the lower carbon alloys, containingabout 0.6- 1.25% carbon, preferably 0.71.25%, the titanium to carordinary amounts.

bon ratio is about 0.3-4: 1. The titanium to carbon ratio in the alloys is thus about 0.3-4: 1. 'Boron may in certain instances be added and serves to replace carbon, and it is to be understood that this equivalent is embraced when reference is made to carbon; Also, titanium will form nitrides, so that it is not available to that extent to combine carbon. It will be understood, therefore, that the titaniumcarbon ratio is exclusive of the titanium which combines with nitrogen. 1

When vanadium is also included, the above-described ratios of vanadium to carbon are effective, that is, the ratio is 24:1 for higher carbon alloys and 1-4:1 for lower carbon alloys, the overall ratio being l-4sl. The proportions of titanium, vanadium and carbon are then selected within the above given limits to provide 1 part by weight of carbon for each 0.74 parts of titanium plus 1 part of carbon for each 2-4 parts of vanadium, in higher carbon alloys, and the overall proportions are 1 part of carbon to 0.3-4 parts of titanium plus 1 part of carbon to l-4 parts of vanadium.

Tungsten or molybdenum is provided in the high speed steel alloys. Tungsten may be employed alone, in a tungsten high speed steel, in-a proportion by weight of 13% to 19%. With the additional incorporation of 2-20% cobalt, 13-22% tugnsten may be provided. Preferably, at least 14% of tungsten is employed. Molybdenum may be employed alone or together with tungsten, in a molybdenum high speed steel, in a proportion of 4% to 9%. With the incorporation of tungsten, the proportion may be 3% to 9%, with the proviso that the sum 2Mo+W= 12.75% to 19%, preferably 14-19%. It is generally preferredthat at least 4.25% of molybdenum be employed. About this amount of molybdenum without tungsten furnishes a relatively low alloy high speed steel of more limited application, and the preferred molybdenum proportion in the absence of tungsten is8-9%.

Chromium is incorporated in a maximum proportion of about 5%. Preferably, about 3.5-5 of chromium is added. Cobalt is very often advantageous andis optionally employed in an amount less than about 20%, preferably less than about 12.5%. When added, the proportion of cobalt is preferably at least about 2%.

The alloys also contain silicon and manganese, in maximum amounts by weight of about 1% of silicon, preferably 0.2-1%, and about 2% of manganese, preferably than about 1.5%. In most steels the sulfur content will be low, say, 0.03% maximum, but it can be added to improve machinability of the steel in amounts up to about 0.5%. The phrases less than and .up to mean that the presence of the element is optional and its'proportion does not exceed that given. The balance of the all-0y will be substantially all iron with residual impurities, such asphosphorus, arsenic and metallic elements, present in The new alloys can be hardened to a Rockwell hardness in excess of C60, andsome, as high as or higher than C67.

' At the same time, they can be annealed to a hardness of under 275 Brinell, at which hardness they are commercially machinable.

In general, the new wear-resistant high speed steel alloys have the following composition:

Carbon 0.6-1.5

Titanium 0.2-6%. Vanadium Up to 6%. Silic 1% max.

.Tungsten with 220% cobalt The carbon content equals 1 part for each 0.3-4- parts of "titanium plus l-part for each 1-4 parts of vanadium. The balance is substantially iron with residual impurities --in "ordinary amounts.

The new tungsten high speed steels have the following composition:

-Carb 0.6-1.5 Titanium (ll-6% vanadium Up to 6%. Silic n 1% max. -Manganese 2% max. Tungs 13% to 19%.

Chr max.

Cobalt Less than 20%. Columbium Less than 1.5%. Sulfur Less than 0.5%. Titanium vanadium 6% total max.

The new molybdenum high speed steels have the following composition:

Titanium may be completely or partly substituted for vanadium in'the common tungsten and molybdenum high speed steels listed on page V of Classification and Symbols 'for Identification of High Speed Steels, 7th 'ed.,

1952 (Gotham Tool (30., Detroit, Mich.). Substitution on an equal weight basis provides better wear resistance, refines the grain size to a greater extent, and provides a marked improvement in cutting-performance. For the amount of vanadium in the high speed steels, preferably in-a titanium-vanadium ratio of about 112.2, and as low as 1:3. With a high level of substitution,approaching maximum replacement of vanadium, the ratio approaches most .part a lesseramount of titanium replaces a given 151, especially in the higher vanadium alloys. ,Th'us,

instead of the normal percentages of vanadium in the standard high spee'd ste'el compositions, the vanadium proportion can be furnished by titaniunralone or both titanium and vanadium according to the formula.

vbols of the corresponding vanadium alloys, having the same amounts of vanadium instead of the titanium:

Tungsten high speed steels W Or T1 00 0 Symbol Percent Percent Percent Percent Percent 18 4 1 0.7 T-l 18 4 2 0. 8 T-2 18 4 2 8 0.8 T-fi .22 4.5 1.5 12 0.8 T-G '18 4 4 1.2 T-9 Molybdenum h gh speed steels Mo Or Ti W 00 Ch 0 Symbol Percent Percent Percent Percent Percent Percent Percent 8.5 4 1 1.5 0.8 M-1 5 4 2 6 0.8 M-2 6 4 2.4-3 6 1 M3 4.5 4.5 4 5.5 1.3 M-4 8 4 2 1.5 0.85 M-7 4.5 4.25 1.5 5.5 1 25 0.8 M-8 8 4 2 0.85 M-10 3 4. 75 5 6. 75 5 1. 5 M-15 The high speed steels also contain silicon and manganese,

partial and complete substitution for vanadium, it was observed that the steels responded to-heat treatment in a manner similar to the other high speed steels, with a slightly higher hardening temperatures required to develop fullsecondary hardness. Thehigher hardening temperatures can be tolerated, since a marked tendency exists to retain a fine grain size and to retain numerous excess carbide particles. The titanium steels are superior in wear resistance to those containing only vanadium. This is apparently due partly to the presence of a large quantity of hard, wear-resistant titanium carbide, titanium nitride and/or titanium carbonitride particles.

Improved results are obtained when 0.2%,preferably 0.4%, or more of titanium is substituted for the same amount of vanadium in the high speed steels. Equivalent or superior results are obtained when about '13%, preferably about 2.2%, of vanadium is replaced by 1% of titanium. Stated in another way, titanium =is substituted for vanadium on the basis of 16% to 1% of titanium, preferably about 'for each 1% of vanadium, with a minimum 'of 0.2%

titanium.

Further exemplary alloys of titanium and of both titanium and vanadium used 'in the manufacture of high speed tools are the following:

W v Mo Or Ti V 00 0 Symbol "Per- "Pen. Per- Percent 7 Percent cent centcent 7 18 0: 1-0:55 0.7 Based-on T-1. 18 02-03 0.5 0.7 -Do.

18 (1.4-0.5 '1 8 0.8 Based on T-j5. 14 F ;0.5 1 15 '..0..75 Based 'onT-B. 13 3 1 5 1.60 Basedon 'I.15 -5.5 0.'7-l.4 2 113 Based an M4. 1.6 0.3 0.5 0.8 ,Basod on Mj-l.

A very advantageous high speed steel similar to M- but new in other respects has the following complete composition:

about 0.5% of sulfur, the total maximum of titanium and vanadium being about 6%, the proportions of titanium, vanadium and carbon being selected within the given l W Mo Or Ti V 00 Mn 81 0 Percent Percent Percent Percent Percent Percent Percent Percent Percent 0.8-1.2 .75-8.25 3.8-4.2 0.6-0.9 1.3-1.7 2.8-3.2 0. 2-0.3 0.2-0.3 1.1-1.16

the balance being substantially iron with residual impurlimits to provide 1 part of carbon for each 0.3-4 parts of ities in ordinary amounts. titanium plus 1 part of carbon for each 1-4 parts of vana- The invention thus provides new and improved highly dium, and the balance substantially iron with residual wear-resistant high speed steel alloys having wide appliimpurities in ordinary amounts. cation, wherein titanium is used as one of the principal 5. A wear-resistant high speed tool steel comprising, alloying elements. The alloys can be hardened to a in proportions by weight, about 0.6 to 1.5% of carbon, Rockwell hardness in excess of C60, and some, as high about 0.2 to 6% of titanium, up to about 6% of vanadas or higher than C67. The alloys have a fine grain size ium, about 0.2-1% of silicon, about 0.1-2% of mangaand improved toughness. The cutting performance of nose, about 13-19% of tungsten, about 3.5-5% of chrotools is markedly improved. The invention constitutes mium, less than about 12.5 of cobalt, less than about a significant advance in the development of high speed 1.5% of columbium, less than about 0.5% of sulfur, the steels for industrial applications. total maximum of titanium and vanadium being about I claim: 6%, the proportions of titanium, vanadium and carbon 1. A wear-resistant high speed tool steel comprising, being selected within the given limits to provide in proportions by weight, about 0.6 to 1.5 of carbon, 1 part of carbon for each 0.3-4 parts of titanium plus 1 about 0.2 to 6% of titanium, up to about 6% of vanapart of carbon for each 1-4 parts of vanadium, and the di about 1% i u f ili n, b ut 2% axibalance substantially iron with residual impurities in mum of manganese, about 13-19% of tungsten, about or inary amounts. 5% im f h i m, l th ab ut 20% of o- 6. A wear-resistant high speed tool steel comprising, balt, less than about 1.5 of columbium, less than about in pr p r n y igh about -6 to 1- f r n 0.5% of sulfur, the total maximum of titanium and about 0 to of titanium, p to a t 6% f vanadvanadium being about 6%, the proportions of titanium, about of S o about 0.1-2% of mangavanadium and carbon being selected within the given nose, obout of molybdenum, about f limits to provide 1 part of carbon for each 03-4 parts chromium, less than about 12.5% of cobalt, less than of titanium plus 1 part of carbon for each 1-4 parts of about 1.5% Of columbium, less than about 0.5% Of sulvanadium, and the balance substantially iron with residual the total maXimum of titanium and Vanadium boiug impurities i ordinary u t about 6%, the proportions of titanium, vanadium and 2, A wear-resistant hi h speed t l t l i i carbon being selected within the given limits to provide in proportions by weight, about 0.6 to 1.5 of carbon, 1 P of carbon each Parts of titanium P about 0.2 to 6% of titanium, up to about 6% of vana- 1 P f carbon for each parts of vanadium, and di about 1% maximum f ili about 2% maximum the balance substantially iron with residual impurities in of manganese, about 4-9% of molybdenum, about 5% ofdluafy amountsmaximum of chromium, less than about 20% of cobalt, A woar-rosisiaut high speed tool Steel Comprising, less than about 1.5% of columbium, less than about In Proporuous y Weight, about to of Carbon, 0.5% of sulfur, the total maximum of tit i d about 0.2 to 6% of titanium, up to about 6% of vanadivanadium being about 6%, the proportions of titanium, about of Silicon, about (ll-2% of mangavanadium and carbon being selected within the given nose, obout 8-970 of molybdenum, about o limits to provide 1 part of carbon for each 0.3-4 parts chromium, less than about 12.5% of cobalt, less than of titanium plus 1 part of carbon for each 1-4 parts of about 15% of columbium, loss than b ut 0.5 of vanadium, and the balance substantially iron with residual l r, the total maximum of titanium and vanadium i i i i di amounts, being about 6%, the proportions of titanium, vanadium 3. A wear-resistant high speed tool steel comprising, u Carbon being selected Within the given limits to P in proportions by weight, about 0.6 to 1.5 of carbon, 1 P of carbon each Po of titanium about 0.2 to 6% of titanium, up to about 6% of vanad- P 1 P of oalbou for each Paris of Vanadium, i about 1% maximum f ili about 2% maximum and the balance substantially iron with residual impuriof manganese, about 13-22% of tungsten, about 5% 111 ordinary amountsmaximum of chromium, about 220% of cobalt, less A woar'rosislanb high Speed tool steel p than about 1.5 of columbium, less than about 0.5% m Proporbous by o b about to 1.5% of carbon, of sulfur, the total maximum of titanium and vanadium about 02 to 6% of titanium, P to about 6% of vanadibeing about 6%, the proportions of titanium, vanadium about of Silicon, about ll-2% of mangaand carbon being selected within the given limits to Rose, :about 13-22% of tungsten, about 3- 5% 0f provide 1 part of carbon for each 0.3-4 parts of titanium chromium, about 242-570 of alt, loss than about plus 1 part of carbon for each 1-4 parts of vanadium, 15% of columbium, 5 than about of Sulfur, and the balance substantially iron with residual impurithe total maxlmum of tltamum and Vanadium being about i i ordinary amounts 6%, the proportions of titanium, vanadium and carbon 4. A wear-resistant high speed tool steel comprising, being Selected Within the given limits to Provide 1 P in proportions by weight, about 0.6 to 1.5 of carbon, of Carbon f r 8 31 03-4 parts of titanium plus 1 part about 0.2 to 6% of titanium, up to about 6% of vanaof carbon for each 1-4 parts of vanadium, and the balance dium, about 1% maximum of silicon, about 2% maximum substantially iron with residual impurities in ordinary of manganese, about 39% of molybdenum, tungsten, amounts. the sum 2Mo-l-W equalling about 12.75% to 19%, 9. A wear-resistant high speed tool steel comprising, about 5% maximum of chromium, less than about 20% in proportions by weight, about 0.6 to 1.5% of carbon, of cobalt, less than about 1.5% of columbium, less than about 0.2 to 6% of titanium, up to about 6% of vanadium, about (h2-,1-%.. of :silicon, about 0.1-2 %1 of manganese, about-314%- ot' molybdenum, tungsten, the. sum 2Mo+W equalling about,l2.75r%totl9%, about 3.54% of chromium, less than about 12.5% of cobalt, less than about 1.5% of columbium, less than about 0.5% of sulfur, the total maximum of titanium and vanadium being about 6%, the proportions of titanium, vanadium,

and carbon being selected within the given limits tq provide 1 part of carbon for each 0.3-4 parts of titanium plus 1 part of carbon for each 1-4 parts of vanadium, and the balance substantially iron with residual impurities ,in rdinary amounts.

1.0. A wear-resistant highspeedptool-steel comprising,

in proportions, byweight, aboutv 1.11.16% of carbon, about 0;6 0. 9,%. of titanium, about 1.'3 1,.7% of-vana: dium, about 02-03% of silicon, about 0.2-0.3 of man: ganese, about 7.75-8.25% of molybdenum, about 0.8,-1.2% of tungsten, about 3,8742% of chromium, about,2.83 .2 of cobalt, and the balance substantially ironwith residual impurities in ordinary amounts.

ReferencesCited in the file. of this patent UNITED STATES PATENTS 

1. A WEAR-RESISTANT HIGH SPEED TOOL STEEL COMPRISING, IN PROPORTIONS BY WEIGHT, ABOUT 0.6 TO 1.5% OF CARBON, ABOUT 0.2 TO 6% OF TITANIUM, UP TO ABOUT 6% OF VANADIUM, ABOUT 1% MAXIMUM OF SILICON, ABOUT 2% MAXIMUM OF MANGANESE, ABOUT 13-19% OF TUNGSTEN, ABOUT 5% MAXIMUM OF CHROMIUM, LESS THAN ABOUT 20% OF COBALT, LESS THAN ABOUR 1.5% OF COLUMBIUM, LESS THAN ABOUT 0.5% OF SULFUR, THE TOTAL AMXIMUM OF TITANIUM AND VANADIUM BEING ABOUT 6%, THE PROPORTIONS OF TITANIUM, VANADIUM AND CARBON BEING SELECTED WITHIN THE GIVEN LIMITS TO PROVIDE 1 PART OF CARBON FOR EACH 0.3-4 PARTS OF TITANIUM PLUS 1 PART OF CARBON FOR EACH 1-4 PARTS OF VANADIUM, AND THE BALANCE SUBSTANTIALLY IRON WITH RESIDUAL IMPURITIES IN ORDINARY AMOUNTS. 